In figuring how much rice to use, take into consideration that adding other elements like vegetables and / or meat will increase the yield considerably. Therefore, 2 cups of rice makes enough for six people.
In calculating for four people, 1.5 cups is plenty. Depending on what you add, you may have leftovers. That's ok. While Italians would never agree with making any more risotto than you eat immediately, I love having some left to quickly heat in the microwave for a quick snack or easy meal.
Be careful about how you heat it up. Know that the texture will not be what it should be for any self-respecting Italian. But great for those of us who love leftovers!
A word about broth: making stock or broth doesn't have to be a long, drawn-out process. It can be as simple as a couple of chicken breasts cooked in 8 cups or so of water with a piece of carrot and celery tossed in. A good trick is to cook the breasts or a couple of legs in a large carton of chicken broth. Even the carton broth by itself makes a wonderful risotto, especially if you are adding two or three elements to the finished risotto.